Comments URL: https://news.ycombinator.com/item?id=43737430

Points: 37

# Comments: 2

You can also safely re-use sub-structures without performing a deep copy. For example, if you want to keep a sub-tree around for later you can do that in O(1) time because it's safe to keep a reference to it. If it is a mutable tree you don't know what's going to happen to it so you need to do a deep copy of the entire sub-tree you're holding on to. This can save a lot on memory allocation and copying depending on your use case.

Also look at any kind of code-gen tooling like parser generators or record specifications like Protocol Buffers as examples of what you could do within the language.

[0] https://docs.oracle.com/javase/tutorial/essential/exceptions...

My other suggestions would be REAMDE for people who are into action movies or spy novels, or the first half of Seveneves for space nerds.

https://en.wikipedia.org/wiki/GADDAG#:~:text=A%20GADDAG%20is....

I'd call it a 4 hour outage because the initial "recovery" was a result of cashiers manually typing in prices for items. Then when load decreased and they discovered that scanning items worked again the problem came right back.

Maybe returning 404 for both a cache miss and a "there's no endpoint at this path" error is an issue too. For other status codes there's a distinction between temporary and permanent failure; e.g. 301 versus 302. It would've been good to use HTTP 400 Bad Request for the misconfigured URL and 404 for a cache miss.

In the 10% of stores with the early roll out of the config change the cache hit rate went to 0 right away, and that started 12 days before the outage. Alerts on cache hit rates and per-store alerts would've caught that.

Then there were 4 days where traffic to the main inventory micro-service in the data center jumped 3x which took it to what appears to be 80% of capacity. Load testing to know your capacity limits and alerts when you near that limit would've called out the danger.

Then during the outage when services slowed down due to too many requests they were taken out of rotation for failing health checks. Applying back pressure/load shedding could have kept those servers in active use so that the system could keep up.

Comments URL: https://news.ycombinator.com/item?id=28189702

Points: 3

# Comments: 0

This strikes a balance where 99% of the time you are making calls that never leave the process for fast testing, but can validate against the real implementation as needed.

So the proposal boils down to $30MM tax free, and then 21.4% on the amount over that. But you're also likely to invest that money making, say, 7%. So your return each year on the first $30MM is 7.0% and is 6.6% on the rest after paying this tax.

"Crema Coffee owner June Tran said bringing her 100-year-old building up to code would cost $100,000."